Doctoral Dissertation Improvement: Primate Social Behavior from an Evolutionary Neuroanatomical Perspective: A Comparative Analysis of the Amygdaloid Complex

有人认为，灵长类动物社会环境中固有的压力推动了人类和非人类灵长类动物新皮层的发展。然而，对人类和非人类灵长类动物行为的功能研究表明，服务于社会行为的神经系统既包括关键的皮层下结构，也包括特定的新皮层区域。不幸的是，这个功能系统的组成部分缺乏信息，这使得很难解决这些对人类行为至关重要的结构的进化发展。提出的分析特别试图通过提供一个重要的皮层下结构——杏仁核复合体的信息来解决这个问题。灵长类动物的杏仁核复合体在调节社会评价和互动中起着关键作用，并与参与社会信息处理的皮质区域高度结合。因此，本研究的目的也反映了神经科学范式的转变，即强调皮层下边缘结构和新皮层之间的功能联系，强调情感和高阶认知的相互依存关系。提出的形态计量学分析将获得所有六种类人猿和三种旧大陆猴种的杏仁核复合体及其五个组成核的无偏体积和神经元计数。由于这五个杏仁核与脑干、嗅觉和新皮层区域的连接方式不同，因此它们可能会表现出不同的扩张，从而导致杏仁核复合体的进化重组。这个项目的智力价值在于它的预期目标是增加对人类和猿类大脑进化的理解，特别是对可能具有适应性意义的区域的理解。虽然大脑是人类适应的重要场所，但我们的近亲——其他五种类人猿（倭黑猩猩、黑猩猩、大猩猩、红毛猩猩和长臂猿）的神经解剖学对比信息却很少。例如，先前对杏仁核复合体的分析只对4个猿类个体进行了体积测量。信息的缺乏限制了大脑进化理论的可测试性，包括那些关注社会压力和认知进化之间相互作用的理论。鉴于该样本包括35个类人猿标本，是迄今为止最大的样本，提出的分析非常适合解决这些问题。此外，该项目将广泛影响科学界，提供新的数据，学生专业知识，组织学系列和实验室设施。这将有助于加州大学圣地亚哥分校人类学系的新湿实验室设施的发展，这将允许生产其他宝贵的类人猿大脑的组织学系列。来自加州大学圣地亚哥分校和索尔克研究所的专家将教这名学生研究人员多种染色技术，以处理动物园和研究机构捐赠的稀有灵长类动物的大脑。形态计量分析的结果将以出版的形式提供给其他研究人员，从分析中产生的系列也可用于其他解剖分析。总的来说，这项研究的结果有望对生物人类学和神经科学以及更大的科学界产生明确的积极影响。

It has been suggested that pressures inherent in the primate social environment have driven the elaboration of the human and nonhuman primate neocortex. Yet, functional studies of human and nonhuman primate behavior indicate that the neural systems subserving social behavior include both critical subcortical structures and specific neocortical areas. Unfortunately, a dearth of information exists for components of this functional system, making it difficult to address the evolutionary development of these structures which are so essential to human behavior. The proposed analysis specifically attempts to address this problem by providing information about an important subcortical structure, the amygdaloid complex. The amygdaloid complex in primates plays a key role in mediating social appraisal and interaction and is highly incorporated with cortical areas involved in social information processing. As such, the aims of this research also reflect a paradigm shift in the neurosciences which have come to stress the functional links between subcortical limbic structures and neocortex, underscoring the interdependence of emotion and higher order cognition. The proposed morphometric analysis will procure unbiased volumes and neuron counts for the amygdaloid complex and five of its constituent nuclei in all six hominoid species and three Old World monkey species. Because these five amygdaloid nuclei are differentially connected to brainstem, olfactory, and neocortical areas, they are expected to show differential expansion resulting in evolutionary reorganization of the amygdaloid complex. The intellectual merit of this project lay in its intended goal to increase understanding of the evolution of the human and ape brain, specifically for regions that may have adaptive significance. While the brain is an important locus for human adaptation, scant comparative neuroanatomical information is available for our closest living relatives, the five other species of hominoids (bonobos, chimpanzees, gorillas, orangutans, and gibbons). For example, previous analyses of the amygdaloid complex have only produced volumetric measures for only four individual apes. This dearth of information limits the testability of theories of brain evolution, including those focused on the interplay between social pressures and the evolution of cognition. The proposed analysis is well suited to address these problems given that the sample, which includes thirty-five hominoid specimens, is the largest to date. Furthermore, this project will broadly impact the scientific community, providing new data, student expertise, histological series, and laboratory facilities. It will contribute to the development of new wet lab facilities in the UCSD Anthropology Department, which will allow for the production of other invaluable histological series of ape brains. Experts from UCSD and the Salk Institute will teach the student researcher multiple staining techniques to process the brains of rare primate species donated by zoos and research institutes. Results of the morphometric analyses will be available in published form to other researchers, and the series produced from the analysis will also be available for use in other anatomical analyses. Overall, the results of this research are expected to have a clear, positive impact on biological anthropology and the neurosciences, as well as the greater scientific community.